The present invention relates to a video signal brancher that is connected to a printer or the like.
The conventional constitution will now be described in conjunction with FIG. 9 which is a block diagram that illustrates a conventional video signal brancher.
In FIG. 9, the video signal brancher (1) is constituted by an image data input terminal (10), an image data branching circuit (11) connected to the image data input terminal (10), a first image data output terminal (12) connected to the image data branching circuit (11), a second image data output terminal (13) connected to the image data branching circuit (11), a synchronizing signal input terminal 14, a synchronizing signal branching circuit (15) connected to the synchronizing signal input terminal (14), a first synchronizing signal output terminal (16) connected to the synchronizing signal branching circuit (15), and a second synchronizing signal output terminal (17) connected to the synchronizing signal branching circuit (15). There are image data signal lines for each of the chrominance signals (R, G, B), and there are signal lines for each of the synchronizing signals (horizontal H, vertical V).
Operation of the above-mentioned conventional example will now be described in conjunction with FIG. 10 which is a block diagram illustrating the condition where the conventional video signal brancher (1) is being used.
In FIG. 10, a printer (2) is connected to the first image data output terminal (12) and to the first synchronizing signal output terminal (16) of the video signal brancher (1), a host computer (4) is connected to the image data input terminal (10) and to the synchronizing signal input terminal (14) of the video signal brancher (1) through a cable (3), and a CRT (6) is connected to the second image data output terminal (13) and to the second synchronizing signal output terminal (17) of the video signal brancher (1) through a cable (5).
There are many kinds of connectors at both ends of the cables (3) and (5), and the most suitable video signal brancher (1) is selected out of the corresponding plurality kinds of ones.
The types of connectors include DIN-type, D-subminiature-type, I-type, etc., and the pin numbers include 9 pins, 15 pins and so on.
A parameter of video signals produced from the host computer (4) is set by operation switches such as numeral keys that are not shown but that are provided in the printer (2) and is stored in the printer (2) such that the image data can be printed by the printer (2). This is done since the type of video signals produced by the host computer (4) vary depending upon the manufacturer.
The video signals include such types as analog and digital signals, interlace and non-interlace signals, and H.V composite and H.V separate signals. Furthermore, even the video signals of the same type have a parameter that is partly different depending upon the manufactures.
The image data branching circuit (11) branches into the CRT (6) the image data out of the video signals produced from the host computer (4), and further branches to the printer (2) the image data from the host computer (4) to the CRT (6).
The synchronizing signal branching circuit (15) branches to the CRT (6) the horizontal synchronizing signals and vertical synchronizing signals out of the video signals produced from the host computer (4), and further branches them to the printer (2) after having shaped their waveforms. FIG. 9 illustrates the case of the H.V separate signals.
As required, the printer (2) prepares output data and prints them based on a parameter that is set and input, based on image data that are input, and based on horizontal synchronizing signals and vertical synchronizing signals.
With the above-mentioned conventional video signal brancher, however, the video signals were simply branched. When video signals of dissimilar parameters were to be printed by the printer, therefore, the parameters of the video signals all had to be sent to the printer each time.